Textural and structural characterization of extrudates from apple pomace, defatted soy flour and corn grits

Corn grits blended with defatted soy flour (30-50%) and apple pomace (0-20%) were extrusion cooked. The effect of apple pomace levels and processing conditions (extrusion temperature, screw speed and moisture content) on the extrudates' textural properties, cellular structure and molecular conformation were studied. Results show that increase in the apple pomace level (0 to 20%) and extrusion temperature (100 to 140 degrees C) decreased the hardness of the extrudates. The hardness ranged between 7.57 and 15.23 N. Lower hardness was associated with higher crispness and brittleness. SEM examination revealed that higher temperature and shear were responsible for the damage of the cellular structure of the extrudates. Presence of air cells indicated crisper extrudates. FTIR showed that there were significant changes in the components in the formulation due to extrusion. This study showed the variation in internal structure and molecular bonds and their effect on the texture of the extrudates containing apple pomace. Practical applications Textural and structural properties of extrudates containing novel blend of apple pomace, defatted soy flour and corn grits were examined. The information generated from this research will help in formulating extruded products with high levels of protein and fiber.